There have been proposed various medicines in the prior art which may be percutaneously absorbed and is effective when applied on the topical site in the human body. These medicines which are intended for topical anesthesia include, for example, an injection, and a liquid, jelly and spray, etc. for use as a surface anesthetic.
However, the latter surface anesthetic is known to provide a remarkable topical anesthetic effect against the mucous membrane of esophagus, stomach and mouth etc. but it is quite ineffective against the topical anesthesia of the skin.
Recently, in the field of anesthesia, the need of pain removal has become a matter of concern when a relatively thick needle is pierced through the skin in such a case where the vena must be punctured to get an access to the vessel, or when the epidural anesthesia and spinal anesthesia etc. must be effectuated. That is, an anesthetic such as lidocaine hydrochloride and procaine hydrochloride etc. have traditionally been dosed to the patient through the syringe, but such procedure cannot avoid causing pain to the patient during a dosing procedure.
With the above-described as a background, the inventor et al of the present patent application has been engaged in the developmental work to provide means which allow lidocaine etc. to be absorbed percutaneously, and tried various substances in order to shorten the time needed for the topical anesthesia to take effect, through an improved percutaneous absorptive effect. As a result, the inventor has found that glycyrrhizin and glycyrrhetic acid, and their derivatives have a remarkable percutaneous absorption improving effect, and thus the present invention has been achieved.